"Sea lamprey attach to fish and they suck their body fluids, so as a parasite they slowly diminish the fish's ability to survive," said U.S. Fish and Wildlife Service biologist Bradley Young.

That’s why federal crews, along with Vermont and New York officials, are trying to keep the population down.

Monday, they sprayed a granular lampricide on targeted areas.

The granuals sink to the bottom and release the pesticide.

"Because the lamprey are living under the sand, it actually lays on the sand and it irritates them," said Young. "Other fish detect it right away and they get out of the way, so they're not very much affected."

Crews are treating the body of water where the Saranac River empties into Lake Champlain because they say it's a ripe breeding ground for sea lamprey.

"It's got both the right habitat for adults to spawn in, and the right habitat for babies, larvae, to rear in," said Young.

He also said that more than a 100,000 lamprey could be breeding in the area.

For two days after the treatment, the Fish and Wildlife Service recommends people and pets avoid lake waters 2 miles north and 3 miles south of the Saranac River mouth, including Cumberland Bay.

Workers scouted the area earlier in the season and took GPS coordinates of where the lamprey were concentrated..

The crew has a new distribution boat that uses that information for precise spraying that they say can be more effective and faster using less product.

"It all runs on GPS, it's got a computer on board so it'll tell you exactly how much you're putting down, where you've put it, where you need to put it," said US Fish and Wildlife Service worker Nicholas Staats.

They say over the past few years they've seen fewer lamprey wounds in fish, which Young says has left more, bigger fish in Lake Champlain.